Mantle issue - MTLValueTransformer won't transform an NSNumber to an int

Question

I'm using Mantle to successfully transform values in my model - but this one comes back with the error: Incompatible block pointer types sending 'int (^)(NSNumber *__strong)' to parameter of type 'MTLValueTransformerBlock' (aka 'id (^)(__strong id)'):

+ (NSValueTransformer *)numDownvotesJSONTransformer
{
    return [MTLValueTransformer reversibleTransformerWithForwardBlock:^(NSNumber *number) {
        return [number intValue];
    } reverseBlock:^(int value) {
        return [NSNumber numberWithInt:value];
    }];
}

This similar transform works fine:

+ (NSValueTransformer *)longitudeJSONTransformer
{
    return [MTLValueTransformer reversibleTransformerWithForwardBlock:^(NSNumber *number) {
        return [NSDecimalNumber decimalNumberWithDecimal:[number decimalValue]];
    } reverseBlock:^(NSDecimalNumber *decimalNumber) {
        return [NSNumber numberWithDouble:[decimalNumber doubleValue]];
    }];
}

Not understanding the difference here.

It seems to me that it requires you to return an object (`id`). `int` is a primitive, not an object. — Ian MacDonald, Feb 12 '15 at 22:06

score 4 · Answer 1 · answered Feb 12 '15 at 22:06

4

Answer from the project's maintainer: "Transformers must operate upon objects. You don't need to do anything for an NSNumber going to a primitive property, because Key-Value Coding takes care of that automatically."

answered Feb 12 '15 at 22:06

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Mantle issue - MTLValueTransformer won't transform an NSNumber to an int

1 Answers1